This invention relates generally to axle assemblies and, more particularly, to certain improvements in welded axle assemblies.
The manufacture of axles for trucks, trailors, and other applications typically involves a combination of welding, machining, and forging operations. For example, a known method involves forging (swaging) a tube or banjo housing on its ends to form a single piece axle/spindle assembly. A flange, such as might be used for braking or wheel mounting, is subsequently attached to the assembly, usually by welding. Another technique involves welding a spindle directly to the ends of a rough forged or machine finished axle tube, followed again by subsequent attachment of the flange. In still another method, two formed halves are joined by welding to produce an axle housing. The spindles and flanges are then attached to the housing by separate welding operations.
A technique for manufacturing an axle assembly by a friction welding process is described in U.S. Pat. No. 4,223,825 to Williams. This method involves welding a spacer tube to a spider, machining the inner bore of the spacer tube to remove material produced by the welding operation, placing the spider/spacer subassembly on the end of the axle tube, and concurrently welding, by friction or inertia welding techniques, a spindle to the spacer and the axle tube.
With the exception of the Williams technique, all of the above discussed methods require a forging operation to directly form the spindle on the axle, or, in the case of separately attached spindles, to reduce the axle end diameter to the spindle diameter for purposes of forming the welded joint. Following attachment or formation of the spindle, subsequent machine or welding operations are required to attach the flange to the spindle/axle assembly. An alternative which reduces or simplifies these manufacturing steps, while providing a structurally advantageous product, is the subject of a related abandoned patent application by the present inventor, Ser. No. 632,224 entitled "Axle Assembly Arrangement" filed on July 19, 1984. To the extent appropriate, pertinent disclosure from that application is hereby incorporated by reference into the present application.
In the method described by Williams, no subsequent welding operation is required to attach the flange since the spindle/axle and the flange (i.e., the spider/spacer subassembly) are joined in a single welding operation. Referring to FIG. 6 of the Williams patent, it can be seen that a single weld 16 is formed to simultaneously join the three components. However, also apparent from this figure is that only the outer surface of weld 16 can be visually inspected when the axle assembly is complete. The weld which join end 25 of the axle beam to end portion 32 of the spindle cannot be visually examined. This is also true for the radial inner portion (29) of the weld which joins inner portion 30 of the axle beam to outer surface portion 31 of the spindle.
Accordingly, an object of this invention is to provide an improved axle assembly arrangement.
Another object of this invention is to provide an axle assembly arrangement which provides for visual inspection of the individual weld joints formed between the axle components.
Yet another object of this invention is to provide an axle assembly arrangement which is compatible with efficient axle manufacturing techniques, such as friction and inertia welding processes.
These and other objects are attained in an axle assembly arrangement which comprises a spindle, a flange, and an axle member. The spindle has an end portion which is generally circular in cross-section and has a first outer diameter, a central portion which is also circular in cross-section and which has a relatively larger outer diameter, and a connecting transition between the two portions. The connecting transition is preferably a step-like transition which forms a radially extending face on the central portion which is subsequently welded to a surface of the flange. The flange has a central bore which is coaxially aligned with, and spaced apart from, an end of the axle member. The end portion of the spindle extends through the central bore of the flange, allowing the radially extending face of the central portion of the spindle to abut the surface of the flange which faces away from the end of the axle member. An end surface of the end portion of the spindle abuts the end of the axle member. A first weld joint is formed between the abutting surfaces of the central portion of the spindle and the flange. A second weld joint is formed between the abutting surfaces of the spindle end portion and the axle member.
A preferred method of manufacturing the axle assembly of the present invention includes the steps of locating an axle member in a first workholding means, locating a flange having a central bore in a second workholding means such that the central bore of the flange is aligned with and spaced apart from an end of the axle, locating a spindle in a third workholding means, positioning the third workholding means such that an end portion of the spindle extends through the central bore of the flange and such that the central portion of the spindle abuts the surface of the flange, welding the central portion of the spindle to the surface of the flange, and welding the end portion of the spindle to the end of the axle. The two welding steps are preferrably performed concurrently. An especially preferred method includes the additional step of removing the welding flash produced by the welding operation from around an outer circumference of at least one weld to allow for a visual inspection of the weld. The welding steps are preferrably performed by friction or inertia welding techniques.
Other objects and advantages of the present invention will be apparent from the following detailed description of a preferred embodiment, when considered in conjunction with the accompanying drawings.